Histo - Muscle Tissue Flashcards
Muscle tissue develops from ____
mesoderm
The cytoplasm in muscle cells is called ___
sacroplasm
What is the sarcoplasm?
the cytoplasm of muscle cells
The smooth endoplasmic reticulum in muscle cells is called _____
sarcoplasmic reticulum
*has new/important role in muscle cells
What is the sarcoplasmic reticulum?
the smooth endoplasmic reticulum in muscle cells
*has new/important role in muscle cells
The plasma membrane / plasmalemma of muscle cells is called _____
sarcolemma
What is the sarcolemma?
The plasma membrane / plasmelemma of muscle cells
What is a muscle cell called?
muscle fiber or myofiber
Describe the difference between a muscle fiber and a nervous fiber
Nervous fiber is just an axon
Muscle fiber is the entire cell
What are the 3 muscle prefixes
sarco-, myo-, mys-
Do muscle organs contain only muscle tissue?
no.
by definition, an organ contains two or more primary tissue types, so it must contain other tissue besides muscle tissue
What are the 3 types of muscle tissue based on functional traits?
1 skeletal muscle tissue
2 cardiac muscle tissue
3 smooth muscle tissue
Describe the contraction of a skeletal muscle tissue
strong, quick, discontinuous, voluntary contraction
Describe the contraction of a cardiac muscle tissue
strong, quick, continuous, involuntary contraction
Describe the contraction of a smooth muscle tissue
weak, slow, involuntary contraction
What are 4 special characteristics of muscle tissue?
1 excitability/irritability
2 contractability
3 extensibility
4 elasticity
Special characteristic of muscle tissue: excitability/irritability.
Describe this.
ability to respond to a stimulus via electrical signal (like a neuronal axon)
can produce/conduct action potentials
Special characteristic of muscle tissue: contractability.
Describe this.
When tension by a muscle is greater than resistance to a force, the muscle shortens
whether or not muscle shortens, contraction is occurring
Special characteristic of muscle tissue: extensibility.
Describe this.
muscle tissue is able to be extended and stressed
*this is a passive process
Special characteristic of muscle tissue: elasticity.
Describe this.
muscle tissue’s ability to return to original length after being shortened or lengthened.
What are the 4 functions of muscle tissue?
1 produce movement
2 maintain posture
3 stabilize joints
4 generate heat
Describe how muscle tissue produces movement (function)
skeletal muscle tissue - moves things from 1 location to another
smooth muscle tissue - moves things within urinary/gi tract through peristalsis
cardiac muscle tissue - move blood throughout cardiac system
Describe how muscle tissue maintains posture (function)
*mostly skeletal muscle
muscles are constantly fighting gravity so muscles must contract to maintain posture
Describe why sitting with your back unsupported leads to back pain
Skeletal muscles play a large role in maintaining posture
If back is unsupported, muscles maintaining posture must do more work, this leads to back pain
Describe why muscle tissue stabilizes joints (function)
*mostly skeletal
because muscles and joints = movement
and muscle tissue plays large role in movement
Describe why muscle tissues generate heat (function)
thermogenesis
muscle cells and tissues are generating ATP to generate a force. this is exothermic
think: shivering at bus stop.
Skeletal muscle: striated/nonstriated? Why?
striated.
because of arrangement of actin and myosin
Describe the cell shape of skeletal muscle cells
large, elongated, cylindrical cells structural syncitiated (multinucleated) cells
elongated because muscle cells run the entire length of the muscle
How long are skeletal muscles?
skeletal muscle cells are elongated.
they run the length of the muscle
Describe nucleus placement of skeletal muscle cells
nuclei are at the periphery just beneath the sarcolemma
Describe why skeletal muscle cells are a structural syncytium
skeletal cells are a fusion of embryonic myoblasts, leading to them being multinucleated
this means that skeletal muscle cells are a STRUCTURAL syncitium
Skeletal muscle cells are a fusion of embryonic _____. This means that they are what?
myoblasts
this means that they are multinucleated aka structural syncitium.
Cardiac muscle cells are a strong, quick contraction followed by _____
quick relaxation period
Describe the cell shape of cardiac muscle cells
elongated, branched cells joined by intercalated discs
Are cardiac muscle cells multinucleated or uninucleated?
uninucleated
occasionally you will see a slide with 2 nuclei in 1 cell, this is rare.
What are intercalated discs? Which muscle cell type are they in?
cardiac muscle
they are eosinophilic lines that connect cardiac muscle cells to each other to keep cells together physically
gap junctions in intercalated discs allow cells to become a FUNCTIONAL syncitium.
this allows cardiac muscle cells to be “interwoven”
Which muscle cell type is a structural syncitium? which is a functional syncitium?
structural syncitium = skeletal muscle cells due to embryonic fusion of myoblasts
functional syncitium = cardiac muscle cells due to intercalated disc’s gap junctions connecting them to each other
Are cardiac muscle cells striated or nonstriated?
striated (seen in longitudinal cross section)
but striation is broken apart by cardiac muscle cell’s branching. so it appears different than skeletal striation
Compare/contrast the striation patterns of skeletal and cardiac muscle cells
Skeletal muscle cells = uninterrupted striated pattern
Cardiac muscle cells = interrupted striated pattern due to branching (mostly) and intercalated discs
Where is the nucleus located in cardiac muscle cells?
Nucleus is centered inside the cardiac muscle cell
Are smooth muscle cells striated or non striated?
Non striated
Their actin and myosin are arranged in a completely different orientation than skeletal/cardiac muscle cells
Are smooth muscle cells uninucleated or multinucleated?
uninucleated.
Describe the cell shape of smooth muscle cells
fusiform (wide centered, tapered on edges)
nucleus is located in the widest part of the fusiform cell
Where are smooth muscle cells found?
in walls of hollow organs needed to proper things forward
gi, urinary, reproductive, respiratory, iris of eye, blood vessels
What is the average length of a smooth muscle cell?
HIGHLY variable
think: can be in blood vessel or in pregnant uterus
How are smooth muscle cells usually oriented with each other?
smooth muscle is usually laid down in “sheets” in same direction with alternating pattern
this is helpful for propelling substances forward throughout a tract
What are the 3 classifications of skeletal muscle in humans?
What are they classified based on?
classified based on physiology, biochemistry, histochemistry
type 1: slow, red oxidative fibers
type 2a: fast, intermediate oxidative-glytolytic fibers
type 2b: fast, white glycolytic fibers
Type 1: slow, red oxidative fibers (skeletal muscle)
describe the amount of myoglobin, mitochondria and glycogen.
many mitochondria and myoglobin present (this is why it is red in color)
What is myoglobin?
oxygen-binding protein
Type 1: slow, red oxidative fibers (skeletal muscle)
Why is it red?
because so much oxygen due to the high levels of myoglobin (oxygen binding protein) and mitochondria
Type 1: slow, red oxidative fibers (skeletal muscle)
derives energy primarily from ____
aerobic oxidative phosphorylation of fatty acids
Type 1: slow, red oxidative fibers (skeletal muscle)
Describe the diameter relative to the other types of fibers
relatively small diameter relative to type IIa and type IIb of skeletal muscles
small = least powerful
Type 1: slow, red oxidative fibers (skeletal muscle)
Adapted for what type of contractions? What’s an example of this?
slow, continuous contractions over long periods of time
example: muscles to maintain posture
Type 2a: fast, intermediate oxidative-glycolytic fibers (skeletal muscle)
describe the amount of myoglobin, mitochondria and glycogen.
many mitochondria, lots of myoglobin AND glycogen (because it is intermediate)
Type 2a: fast, intermediate oxidative-glycolytic fibers (skeletal muscle)
Describe the diameter relative to the other 2 fibers
Diameter size is intermediate between type I and type IIb skeletal muscle fibers
Type 2a: fast, intermediate oxidative-glycolytic fibers (skeletal muscle)
derives energy primarily from ___
oxidative metabolism and anaerobic glycolysis
intermediate
Type 2a: fast, intermediate oxidative-glycolytic fibers (skeletal muscle)
Adapted for what type of contractions?
Rapid contractions and short bursts of activity
Type 2b: fast, white glycolytic fibers (skeletal muscle)
describe the amount of myoglobin, mitochondria and glycogen.
Fewer mitochondria and myoglobin
LOTS of glycogen (which makes it pale or white looking)
Type 2b: fast, white glycolytic fibers (skeletal muscle)
Why is it white?
because of the glycogen present
Type 2b: fast, white glycolytic fibers (skeletal muscle)
Energy is derived primarily from _____
anaerobic glycolysis
Type 2b: fast, white glycolytic fibers (skeletal muscle)
Adapted for what type of contraction/ What is an example of this?
Rapid contractions (that fatigue easily)
Example: weight lifting, throwing baseballs, etc.
Most muscles contain which type of muscle fiber?
most muscles are a combination of muscle fiber types
may have more of one type depending on it’s function and/or genetics
Myofibrils take up ___% of cytoplasm?
80